Some of the increase is attributed to better identification and diagnosis, the researchers said, but how much is due to those factors is unknown.

Since the CDC’s first report in 2007, there has been a 78 percent increase.

The CDC report is based on information from monitoring networks in 14 communities that collect information on 8-year-olds diagnosed with developmental disabilities or autism spectrum disorders.

In 2000, about 1 in 150 children were identified with autism spectrum disorders. That rose to 1 in 125 in 2004 and to 1 in 88 in 2008 – the year the current report is based on.

Findings from the report include:

• The number of children identified with ASDs varied widely across the network sites, from 1 in 47 to 1 in 210.
• ASDs are almost 5 times more common among boys (1 in 54) than among girls (1 in 252).
• The largest increases over time were among Hispanic children (110 percent) and black children (91 percent). Some of this increase is believed to be due to greater awareness and better identification among these groups. However, more children are being identified in all groups.
• There were increases over time among children without intellectual disability (those having IQ scores above 70), although there were also increases in the estimated prevalence of ASDs at all levels of intellectual ability.
• More children are being diagnosed at earlier ages—a growing number of them by age 3. Still, most children are not diagnosed until after they reach age 4, even though early identification and intervention can help a child access services and learn new skills.

The CDC urges parents to follow its program, Learn the Signs. Act Early. It provides information to help parents track their child’s development, so early intervention is possible if help is needed.